Given below are two statements:
Statement I: [CoBr₄]²⁻ ion will absorb light of lower energy than [CoCl₄]²⁻ ion.
Statement II: In [CoBr₄]²⁻ ion, the energy separation between the two set of d-orbitals is more than [CoCl₄]²⁻ ion.
In the light of the above statements, choose the correct answer from the options given below :

Question

Statement-I: An element ‘X’ of P-block forms a hydride H–X, which has the longest bond length, then element ‘X’ will have the shortest covalent radius.
Statement-II: An element ‘E’ of Group 15 forms hydride EH$_3$, that has least B.P. The maximum covalency of E is 4.

Answer 1

To solve this question, we need to analyze the nature of the two complex ions, [CoBr₄]²⁻ and [CoCl₄]²⁻, and understand how the ligands influence the properties and behavior of these complexes.

Both [CoBr₄]²⁻ and [CoCl₄]²⁻ are tetrahedral complexes with cobalt in the +2 oxidation state. The key factor here is the nature of the ligands: bromide (Br⁻) and chloride (Cl⁻).
The ability of a ligand to split the d-orbitals in a metal complex is quantified by the spectrochemical series. In the spectrochemical series, Cl⁻ is a weaker field ligand compared to Br⁻. Hence, Cl⁻ will cause less splitting of the d-orbitals than Br⁻.
Since Br⁻ is further down in the spectrochemical series compared to Cl⁻, we can infer that in tetrahedral complexes like these, Br⁻ will cause a lesser degree of splitting compared to Cl⁻.
In Statement I, it is mentioned that [CoBr₄]²⁻ will absorb light of lower energy than [CoCl₄]²⁻. Lower energy light corresponds to a smaller energy gap ($\Delta$) between the split d-orbitals, which supports the fact that the [CoBr₄]²⁻ complex has less splitting.
Thus, Statement I is true: [CoBr₄]²⁻ will indeed absorb light of lower energy than [CoCl₄]²⁻ due to the smaller energy gap.
Contrastingly, Statement II claims that the energy separation in [CoBr₄]²⁻ is more than in [CoCl₄]²⁻. This contradicts the established reasoning that [CoBr₄]²⁻ has less splitting compared to [CoCl₄]²⁻.

Therefore, Statement II is false. The larger separation occurs in [CoCl₄]²⁻ due to the weaker field strength of Cl⁻ compared to Br⁻ in a tetrahedral coordination environment.

In conclusion, the correct answer is: Statement I is true but Statement II is false. This highlights the importance of understanding the impact of ligand field strength on the splitting of d-orbitals in metal complexes.

Answer 2

To solve this question, we need to analyze the nature of the two complex ions, [CoBr₄]²⁻ and [CoCl₄]²⁻, and understand how the ligands influence the properties and behavior of these complexes.

Both [CoBr₄]²⁻ and [CoCl₄]²⁻ are tetrahedral complexes with cobalt in the +2 oxidation state. The key factor here is the nature of the ligands: bromide (Br⁻) and chloride (Cl⁻).
The ability of a ligand to split the d-orbitals in a metal complex is quantified by the spectrochemical series. In the spectrochemical series, Cl⁻ is a weaker field ligand compared to Br⁻. Hence, Cl⁻ will cause less splitting of the d-orbitals than Br⁻.
Since Br⁻ is further down in the spectrochemical series compared to Cl⁻, we can infer that in tetrahedral complexes like these, Br⁻ will cause a lesser degree of splitting compared to Cl⁻.
In Statement I, it is mentioned that [CoBr₄]²⁻ will absorb light of lower energy than [CoCl₄]²⁻. Lower energy light corresponds to a smaller energy gap ($\Delta$) between the split d-orbitals, which supports the fact that the [CoBr₄]²⁻ complex has less splitting.
Thus, Statement I is true: [CoBr₄]²⁻ will indeed absorb light of lower energy than [CoCl₄]²⁻ due to the smaller energy gap.
Contrastingly, Statement II claims that the energy separation in [CoBr₄]²⁻ is more than in [CoCl₄]²⁻. This contradicts the established reasoning that [CoBr₄]²⁻ has less splitting compared to [CoCl₄]²⁻.

Therefore, Statement II is false. The larger separation occurs in [CoCl₄]²⁻ due to the weaker field strength of Cl⁻ compared to Br⁻ in a tetrahedral coordination environment.

In conclusion, the correct answer is: Statement I is true but Statement II is false. This highlights the importance of understanding the impact of ligand field strength on the splitting of d-orbitals in metal complexes.

Show Hint

The Correct Option is C

Solution and Explanation

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